The present invention relates in general to resinous compositions such as asphalt, coal tar and/or elastomeric compositions, and more specifically, relates to a unique resinous cut-back composition for ambient temperature application to substrates wherein the composition comprises an environmentally safe and biodegradable terpene solvent.
Resinous or residue-based compositions such as those comprising asphalt, polymer modified asphalt, coal tar, natural rubber and elastomers are widely utilized for construction and industrial purposes. Examples of such compositions include hydrocarbon-based sealants, adhesives, cements, mastics, caulking, waterproofing agents, primers and protective aluminum coatings. Such compositions need exhibit good adhesion to the substrates upon which they are applied and should be generally resistant to deterioration over time. The compositions need to have some amount of elasticity and flexibility to avoid cracking and failure when exposed long-term to any number of environmental stresses such as wind, rain or the contraction and expansion of surrounding substrates.
For years these resinous compositions have tended to be solvent blends, also known as "cut-backs", wherein the asphalt or other resinous component is blended with a solvent to increase the fluidity of the composition and enable easy "cold-pour" application at ambient temperatures. The solvent evaporates following application leaving the asphalt residue firmly in place as an adhesive, coating or similar material.
Highly volatile compounds (VOCs) such as aromatic and chlorinated hydrocarbon solvents, including xylene, trichloroethane, toluene, methyl-ethyl ketone and butyl acetate have traditionally been utilized in cut-back formulations. These solvents have proven useful since they readily evaporate following application to leave a relatively dry adherent residue in a short amount of time. Yet due to the potentially carcinogenic, toxic and high VOC character of many aromatic and chlorinated hydrocarbon solvents, the use of such solvents for construction and industrial purposes is now closely scrutinized by the Occupational Safety and Health Administration (OSHA). Furthermore, these solvents are the subject of stringent hazardous chemical regulations because they are highly volatile, not readily biodegradable and are photochemically reactive. Another disadvantage of using such solvents is that some construction materials, such as roofing membranes for example, can be damaged by intimate contact with these strong solvents.
In view of the environmental, health and quality concerns heretofore described, less dangerous solvents such as mineral spirits have been used to provide resinous cut-back compositions. The mineral spirits is less toxic and volatile than solvents used in the past, and therefore release a smaller amount of VOCs into the environment. Although the reduced volatility is preferred for environmental and safety reasons, the mineral spirits evaporates slowly over a long period of time which detracts from the overall effectiveness of the composition. For instance, when applying an adhesive, a slower evaporation time delays set-up of the composition and inhibits complete bonding between joined surfaces. As a result of this extended drying period, the construction has poor wind resistance or is otherwise vulnerable to environmental factors.
To eliminate these drawbacks, some asphalt or modified asphalt compositions are provided as "hot-melt" compositions. The "hot-melts" are prepared by heating the asphalt to relatively high temperatures in excess of 300.degree. F. and applying the composition while hot. The composition is fluid at such high temperatures enabling application of the composition without the need for volatile and dangerous solvents. Although these "hot-melt" compositions are readily used commercially, they require heating equipment, such as oil jacketed double boilers with oil being used as the heating medium, at the work site. Another problem associated with the use of these heaters and hot asphalt materials is the risk of fire and accidental burn injuries. In addition, careful control of the heating of the heat transfer oil and of the hot-melt composition must be exercised to prevent overheating. Even with proper heating control, the physical characteristics of these rubbery compositions, such as elasticity and resilience, can often be reduced by thermal degradation which accompanies high temperature maintenance for relatively long periods of time.
It is therefore an object of the present invention to provide a resinous composition that is both environmentally safe and that can be applied at ambient temperatures.
A further object of the present invention is to provide a resinous composition which sets-up to provide a resistant and otherwise strong bond in a relatively short period of time following application.
Another object of the present invention is to provide a resinous or residue-based composition that comprises a relatively high amount of solids to minimize shrinkage following application.
Still another object of the present invention is to provide a resinous composition that avoids the use of dangerous highly volatile organic chemicals which pose an environmental threat and expose the applicator to health risks.
It is a further object of the present invention to provide a resinous or residue-based composition that contains a biodegradable solvent which exhibits relatively low toxicity and non-corrosiveness.
Yet another object of the present invention is to provide a resinous composition which comprises a solvent that has a relatively low-level or minimal VOC release.
Still a further object of the present invention is to provide a resinous composition comprising a solvent that is not photo-chemically reactive as to destroy or otherwise effect the ozone layer.
It is another object of the present invention to provide a resinous composition that can be easily handled and applied without special heating equipment.
Another object of the present invention is to provide a resinous or residue-based composition that does not deteriorate over time and does not destroy or alter construction materials used therewith.
It is another object of the present invention to provide a resinous composition that exhibits good elasticity, stress relaxation, superior bond and adhesion to substrates even at relatively low temperatures.
A further object of the present invention is to provide a method for preparing a resinous composition meeting all of the above and foregoing objects.